🧱Build — tap a turret, then a lit edge tile beside the path.
⬆️Upgrade — a yellow light blinks when you can afford it. Tap a turret to upgrade or sell.
👾Enemies — runners, tanks, shielded orbs, healers, and bombers that wreck nearby turrets.
💀Boss every 5th wave — a giant of a new type each time.
⚡Overcharge (key O) blasts the field when it gets hairy.
🔓Unlocks — Sniper at wave 10, Support at 20, and more beyond.
💰Gold — earn interest between waves, or Send Next early for a bonus.